Numerous devices are known to prevent forced entry through a partially open door. One common device of this type is the door chain. One end of the door chain is typically attached to a plate which is fastened by screws or the like to the door jamb or casing. The other end of the chain is releasably connected to a bracket or the like mounted on the inside face of the door, from which the end of the chain may be disconnected only when the door is completely closed. The length of the chain is such that the door may be partially opened with the chain fastened to the door.
However, door chains typically provide poor protection against forced entry. Forces exerted on the outside of the door have been known to break the chain itself or break the chain free from its supports. Even if the door chain is strong enough to withstand such forces, it may be sawn through or cut with a metal cutter or the like.
Other devices have been developed which are superior to door chains in terms of protection against forced entry. Typical devices of this type are shown in U.S. Pat. No. 5,490,304 issued Feb. 13, 1996 to Winner, Jr. et al., and U.S. Pat. No. 5,590,918 issued on Jan. 7, 1997 to Kambalov. Both of these patents relate to floor mounted doorstops which secure a completely closed door and also allow the door to be opened a small amount while keeping it secured against forced entry.
The floor mounted doorstop described by Winner, Jr. et al. comprises a vertical post inserted into a sleeve embedded in a joist below the floor. The top of the vertical post is provided with a horizontal sleeve through which extends a pivoting member. When the pivoting member is pivoted into engagement against the closed door, it provides protection against forced opening of the door while the door is closed. When the pivoting member is pivoted away from the door, the door may be opened by a small amount until it contacts the vertical post of the door stop.
Kambalov describes a similar device having a vertical post extending below the floor. A horizontal cam having a plurality of surfaces is eccentrically connected to the top of the vertical post. The cam may be rotated into engagement with the door, in which position it provides protection against forced entry when the door is completely closed. When the cam is rotated out of engagement with the door, the door may be opened by a small amount.
While the devices provided by Kambalov and Winner, Jr. et al. provide protection against forced entry both when the door is closed and when the door is partially open, they have several disadvantages. Firstly, the Kambalov and Winner, Jr. et al. devices may only be operated from inside the door. Therefore, these devices are only useful when the occupants of the house or apartment in which they are installed are at home. Secondly, in order to completely open the door, the Kambalov and Winner, Jr. et al. devices must be completely removed from the floor and be set aside where they will not interfere with the swinging door.
Therefore, the disadvantage exists that known devices for preventing forced entry through a partially open door are inconvenient to use and/or provide insufficient protection against break-ins.
A further disadvantage exists in that devices which prevent forced entry through either a closed or partially open door do not provide protection against forced entry while the occupants are out.